This invention relates to a condensate drain leg assembly or drain trap for a condensing combustion apparatus.
Recently, the pulsating combustion process has been adapted for devices such as high energy efficient residential water heaters and gas fired furnaces. In gas-fired furnaces utilizing the combustion process, gas and air enter the combustion chamber via flapper control valves and mix in the combustion chamber. A spark is used to ignite the gas and air in the combustion chamber initially. Positive pressure from the combustion process within the combustion chamber closes the flapper control valves and forces exhaust gas down a tail pipe extending from the combustion chamber. The exhaust gas or combustion product leaving the combustion chamber create a negative pressure. This opens the flapper control valves to draw gas and air into the combustion chamber. This new gas air charge is ignited by residual combustion in the combustion chamber. No spark is needed for the second ignition. The process repeats itself without continued use of the spark plug or purge air blower. From the tail pipe, the exhaust gases pass to an exhaust decoupler, which is part of the sound reduction system of the gas-fired furnace. The exhaust gas is cooled from about 700.degree. F. to about 350.degree. F. The exhaust gas from the exhaust decoupler is forced through a condensing coil. As the temperature of the exhaust gas reaches the dew point in the condensing coil, water is condensed from the gases allowing reclaimation of the latent heat of combustion.
A drain leg assembly has been provided, as shown for example in Cherington Pat. No. 4,479,482, to separate flue gases from the condensate discharged from condensing furnace. The drain leg assembly of the type shown in the Cherington patent has been referred to as a P-trap. A drain vent was associated with the outlet drain leg assembly in order to vent the condensate outlet to the atmosphere.
The Eising Pat. No. 4,627,460 suggests providing a condensate discharge device for a condensing apparatus which includes a housing with a plastic ball therein to prevent escape of gas from the housing. When condensate accumulates above a predetermined level in the housing of Eising, the ball will float to permit the discharge of condensate from a condensate outlet while preventing discharge of the exhaust gas through said condensate outlet. The Eising condensate discharge device includes a vent tube or drain vent associated with the condensate outlet in order to vent same to the atmosphere.
Other patents show traps with ball valves. For example, Callicott 1,374,079 and Kieselbach 1,789,706 show steam traps. Wesson 2,021,342 reveals a vacuum preventing valve. Holtman 2,325,956 pertains to a device for preventing back flow in liquid carrying lines. Powers 3,209,738 shows a device for draining condensed water vapor from an automotive crank case ventilation system. None of these patents relates to a condensate drain leg assembly for a condensing device and none suggests the structure of the present invention.
An object of the present invention is to provide an improved condensate drain leg assembly for use with a condensing gas-fired furnace.
Another object of the present invention is to provide an improved condensate drain leg assembly or condensate trap for a condensing furnace or like device which incorporates a drain orifice for forming a dam in the condensate outlet to stabilize the float valve in the condensate drain leg assembly and prevent negative pressure from undesirably unseating or dislodging the float valve.
A further object of the present invention is to provide an improved condensate drain leg assembly which incorporates a drain orifice for forming a dam in the condensate outlet to prevent air from being drawn back into the condensate drain leg assembly and undesirably unseating the float valve in the condensate drain leg assembly.
Another object of the present invention is to provide an improved condensate drain leg assembly for a condensing furnace which includes a housing having a chamber with an outlet opening therein, a float valve adapted to close the outlet opening, a condensate outlet extending generally perpendicularly from the bottom of the housing assembly and a drain orifice in the condensate outlet forming a dam for maintaining a condensate level at least as high as the bottom of the outlet opening to prevent undesirable noise.
Still another object of the invention is to provide a condensate drain leg assembly that is compact so that it is better able to be accommodated within a condensing furnace.
A further object of the present invention is to provide a compact, durable, and relatively inexpensive condensate drain leg assembly that may be easily field assembled and installed in a condensing furnace.
Other objects and advantages will be made more apparent hereinafter.